Aminoalkane diphosphonic acids and their salts, possibly also containing a hydroxy group, are gaining increasing interest in recent times because of their good efficiency as complex formers, in particular also in substoichiometric quantities (threshold amounts); as well as in pharmaceutical products.
Compounds of this kind are, for example, the 3-aminoalkane-1,1-diphosphonic acids such as 1,3-diaminopropane-1,1-diphosphonic acid or 3-amino-1-hydroxypropane-1,1-diphosphonic acid. Despite their good effectiveness, these known compounds are not satisfactory in all properties. For example, they have only a moderate threshold effect at low dosages. Besides, in certain pH ranges, relatively poorly soluble alkaline earth complexes occur in part.